Keyword cannibalisation is the practice of using the same word or phrase you wish to rank for on multiple pages of a website. This dilutes the effectiveness of ranking efforts, as Google cannot understand which page is the most relevant for a query. It is often done unintentionally, but nonetheless negatively impacts SEO.
It is a common misconception that Google will, as a result, choose to display more than one of these pages for a query at one time. On the contrary, Google will select what it identifies as the best page to present to the user. This means your pages are in fact competing against each other.
Furthermore, these pages may not all be equally relevant for that term. This can result in reduced visibility, as Google identifies these pages are not particularly relevant for the keyword. This also harms the user experience, as the page may not meet user expectations.
The benefits of acquiring backlinks across these pages are also reduced, as any ranking benefits will be spread across multiple pages, reducing their potency.
If content is also repeated across these pages, you are also at risk of increasing duplicate content issues. This can make it even harder for Google to understand which page you wish to rank.
It may be the case that one page in particular is converting better than other pages. If so, you may be wasting time focusing energy on other pages, when you could focus on the single highest-converting page and further improve it.
Each page on your site should be optimised for unique keywords throughout metadata and content. This will make your content clearer to search engines, aiding your rankings and ultimately traffic, while also making your site easier to understand and navigate for users.
How to fix it
If a business realises their site has instances of keyword cannibalisation, there are several ways they can fix it.
They may decide to review the website structure and the keywords each page is optimised for. This may involve doing keyword research to discover new, relevant keywords for the cannibalising pages.
301 redirects can also be put in place to permanently redirect users from the cannibalising pages to more relevant pages, optimised for different keywords. This means if a user navigates to the old page, they would be taken to the new page. The old page would also disappear from the search engine index, and the new page would become indexed.
Whatever method is used, it’s important to remember that the damage isn’t permanent, and changes can always be made to improve a business’ organic visibility.